CLINICAL USE OF LOCAL ANESTHETICS. Edited by Asadolah Saadatniaki

Transcription

1 CLINICAL USE OF LOCAL ANESTHETICS Edited by Asadolah Saadatniaki

2 Clinical Use of Local Anesthetics Edited by Asadolah Saadatniaki Published by InTech Janeza Trdine 9, Rijeka, Croatia Copyright 2012 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. As for readers, this license allows users to download, copy and build upon published chapters even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. Notice Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Maja Jukic Technical Editor Teodora Smiljanic Cover Designer InTech Design Team First published March, 2012 Printed in Croatia A free online edition of this book is available at Additional hard copies can be obtained from orders@intechopen.com Clinical Use of Local Anesthetics, Edited by Asadolah Saadatniaki p. cm. ISBN

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5 Contents Preface VII Chapter 1 A New and Enhanced Version of Local Anesthetics in Dentistry 1 Tülin Satılmış, Onur Gönül, Hasan Garip and Kamil Göker Chapter 2 Local Anesthesia for Cosmetic Procedures 11 Dhepe V. Niteen Chapter 3 Repair of Incisional Hernias of the Midline Under Local Anesthesia in an Ambulatory Basis 29 Alberto F. Acevedo Chapter 4 Urological Surgical Procedures Under Local Anesthesia 39 M. Hammad Ather, Ammara Mushtaq and M. Nasir Sulaiman Chapter 5 Local Anesthesia for the Prostate Gland 59 Allison Glass, Sanoj Punnen and Katsuto Shinohara Chapter 6 Achilles Tendon Repair Under Local Anesthesia 75 Andrej Čretnik Chapter 7 The Use of Topical Cream Anesthetics in Office Procedures of the External Genitalia 87 Kostis Gyftopoulos

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7 Preface From the time of cocaine as the first local anesthetic till now, many local anesthetics have been introduced to clinical practice. Pharmacologic properties of local anesthetics, such as pharmacokinetic and pharmacodynamic properties, have progressed toward the shorter onset, longer duration, higher potency and lower side effects in newer local anesthetics. Alongside the pharmacologic advancement in newer drugs, clinicians are innovatively utilizing local anesthetics in different fields and in unique states for various surgeries. This book is an effort to gather the application of local anesthetics in various surgical procedures such as dentistry, plastic surgery, liposuction, hair transplantation, herniorrhaphy and urologic and orthopedic surgeries that are based on the experience of the authors. These local anesthetics have been applied as topical gel, ointment, spray, and so forth. By considering the content of this book, we think that other procedures which are performed by the use of local anesthetics, such as minimally invasive spinal surgeries, arthroscopy, endovascular procedures and veterinary operations, have the indication for further studies in future clinical trial surveys. Asadollah Saadatniaki, M.D Associate Professor of Anesthesiology Director of Pain Education Program in Shahid Beheshti University of Medical Sciences, Tehran, Iran Acknowledgement I greatly appreciate the contribution of my colleague Dr. Alireza Mirkheshti, for his assistance in reviewing the chapter proposals.

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9 1 A New and Enhanced Version of Local Anesthetics in Dentistry Tülin Satılmış, Onur Gönül, Hasan Garip and Kamil Göker Faculty of Dentistry, Department of Oral and Maxillofacial Surgery Marmara University, Istanbul Turkey 1. Introduction Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. Due to the fear of pain associated with dental injections, some people avoid, cancel, or fail to appear for dental appointments. Pain and anxiety control are among the most important aspects in local anesthetic administration in dental practice. Administration of local anesthetic produces pain and anxiety that may cause subsequent unfavorable behavior (1). As reliable management of pain is an important factor in reducing fear and anxiety in dental treatment, clinicians must have a thorough knowledge of local anesthetic solutions and techniques. When an agent and a technique are chosen, it is important for the clinician to understand the onset, depth, and duration of anesthesia in relation to the operative procedure to be performed (2). This chapter introduces new local anesthetic formulations, techniques, and postinjection complications in dentistry. 2. Pharmacologic properties of local anesthesia The main working principle of local anesthetics is to inhibit the ion flow on nerve cell membranes to stabilize membrane potential and block stimulus conduction. Local anesthetics can be defined as compounds capable of reversibly suspending the ability of the nerve tissue to conduct stimuli (3). Local anesthetics consist of a lipophilic aromatic part, which is responsible for the affinity of the compound to the nerve cells, joined by a connecting chain to a hydrophilic part that is responsible for solubility in water and diffusion among tissues. Decomposition of the compound is affected by the nature of the connecting chain, leading to changes in properties such as duration of action or toxicity. Local anesthetics can be divided into two groups according to the nature of the chemical bonding: esters (e.g., procaine) and amides (e.g., lidocaine) (3 4). The therapeutic value of such compounds is determined by the typical pharmacological properties of local anesthetics. The compound with the longest history of clinical use,

10 2 Clinical Use of Local Anesthetics procaine, is used as the basis for comparisons of novel agents. The minimum concentration at which the anesthetic can block stimulus conduction (potency), the therapeutic value of the compound in terms of the correlation between efficacy and tolerability (toxicity), ability of the anesthetic compound to reach tissues at some distance from the site of administration (diffusibility), duration of anesthesia (duration of action), and metabolism of the anesthetic compounds are commonly compared as general pharmacological properties of local anesthetics (3 6). Vasoconstrictors are added to local anesthetic solutions to inhibit absorption and thus prolong the duration of action and reduce the toxicity of anesthetics as well as to achieve a suitable blood-free area for surgery. Therefore, it is necessary to take into consideration that reactive vasodilatation may occur after surgery with usage of local anesthetics with added vasoconstrictors (7 8). Adrenaline is the most commonly used vasoconstrictor worldwide. Local anesthetic solutions generally contain adrenaline at a concentration of 1 part per or 1 part per , resulting in a final content of mg in 1 ml of anesthetic solution. Thus, anesthetic solutions contain adrenaline at very low concentrations compared to the levels required for general physiological effects in healthy individuals ( mg by subcutaneous administration). There is a great deal of controversy regarding contraindications for the use of adrenaline-containing anesthetics. The mode of administration and quantity added must also be taken into consideration. The American Dental Association and American Heart Association recommend an upper limit of 0.2 mg of adrenaline to be administered in dental operations. On the other hand, the low potency of anesthetic solutions without adrenaline may lead to pain and elevated levels of stress during the operation, resulting in enhanced release of catecholamine (8). Noradrenaline is another vasoconstrictor used in anesthetic solutions, which has a much weaker local vasoconstrictor effect than adrenaline. Noradrenaline is therefore applied at higher concentrations in anesthetic solutions. The most important advantage of noradrenaline is that it has no direct effect on the cardiovascular system (6 8). 3. Clinical properties of local anesthetics This section discusses the characteristic clinical properties of the most commonly used local anesthetics. Procaine: Procaine was synthesized by Einhorn in 1905 and is important in the history of the development of local anesthetics, as it was the first compound to be used in humans. Although it has been superceded in dental practice by more effective modern drugs, the clinical properties of such drugs are still compared with those of procaine as a baseline. Procaine is weaker than modern products currently in use in clinical practice. It is highly soluble in water, and its hydrochloride salt is used as a local anesthetic. It has a low toxicity level and a relatively short duration of action (3,7). Lidocaine: Lidocaine is currently the most widely used local anesthetic in clinical practice throughout the world. First synthesized by Löfgren and Lundquist in 1943, its potency is

11 A New and Enhanced Version of Local Anesthetics in Dentistry 3 fourfold greater than that of procaine, and its toxicity is double that of procaine. The duration of action of lidocaine is double that of procaine, and it shows good diffusibility (4). Articaine: This preparation, introduced to medical practice by Muschavek and Rippel in 1974, has similar potency, toxicity, and duration of action to lidocaine. Articaine is used almost exclusively in dental practice (7). Bupivacaine: The toxicity of bupivacaine is ten times that of procaine and has a longer duration of action than lidocaine (7). Mepivacaine: The potency and toxicity of mepivacaine are similar to those of lidocaine. This agent has a mild vasoconstrictor effect, which leads to a prolonged duration of action (5,6). Prilocaine: Prilocaine is used in dentistry as a 4% solution containing a vasoconstrictor. This agent has potency equivalent to that of procaine and a toxicity level slightly lower than that of lidocaine and 1.5 times that of procaine (7). 4. Methodology of local anesthesia Local anesthesia can be classified into two groups according to the manner in which the clinician wants to reach the nerve elements to be anesthetized. The term terminal anesthesia, also called infiltration anesthesia, is used to explain the mode of anesthesia in which the nerve elements are reached at their organ endings, such as the tooth and the periodontal membrane. Practically, there are a number of variants, i.e., topical anesthesia, submucosal infiltration, intramucosal infiltration, and block anesthesia. The term block anesthesia is used to explain blocking of peripheral nerve conduction along the nerve s course. The anesthetic solution is administered at a site some distance from where the clinician wishes to apply the anesthesia (6,7,8,12). 4.1 Anesthesia of upper teeth In accordance with the maxillary bone structure, anesthesia of the upper teeth is generally performed terminally. The maxilla is covered by a thin cortical layer, and the internal structure of the bone is sponge-like, which facilitates diffusion of local anesthetic solution. The alternative possibility is the nerve-block method, which can be performed in some cases after careful consideration of the advantages and associated risks (7). 4.2 Anesthesia of lower teeth In contrast to the maxilla, the anatomic structural properties of the mandible force the practitioner to utilize nerve-block anesthesia methods instead of terminal anesthesia. The cortical bone layer that surrounds the mandible is thicker than the maxilla, and the nerve fibers lie in deeper bone structures, leading to poor performance of terminal anesthesia because of the lack of diffusion of the anesthetic solution into deeper parts of the mandible. Therefore, it is essential to be familiar with the anatomical structures and supply areas of the nerves to be affected when performing local anesthesia in the mandible. There is still

12 4 Clinical Use of Local Anesthetics disagreement regarding whether terminal or nerve block anesthesia is the most appropriate method for the lower incisors (9 11). 4.3 Complications of local anesthesia Although local anesthesia is commonly defined as a safe and noninvasive procedure, some complications have been reported that can be classified into two groups: general and local (7). General complications are related to the nature and composition of the local anesthetic solution. The most important general complications are toxic and allergic in nature, both of which are capable of causing death in severe cases. Toxic reactions are rarely seen in dentistry, as the quantities of anesthetic agents applied in dentistry and oral surgery are generally within safe limits. If overdosing occurs, central nervous system effects predominate, and spasms, loss of consciousness, and respiratory depression may occur. It is important not to confuse the overdose reactions with those caused by vasoconstrictors. Allergic reactions are the other most important general complications of local anesthesia. Although allergic reactions caused by local anesthetic solutions with amide linkages are extremely rare, clinicians should always be aware of the symptoms of allergic reactions, especially in patients with a history of polysensitivity to other compounds (11 14). The most common local complications of local anesthesia in dentistry and oral surgery practice are hematoma, nerve damage, trismus, facial paralysis, and tongue and lip injuries. These local complications may be due to the method of anesthesia used, injury to adjacent anatomical structures, or administration of local anesthetic to an inappropriate site (11 14). 4.4 Volume of local anesthesia Local anesthesia is not always effective in dentistry. The success of inferior alveolar nerve block ranges from 53% to 100%. A higher degree of success would be expected with infiltration anesthesia. Nevertheless, infiltration injection is not always 100% successful. This can be explained by differences in the smoothness, density, porosity, and thickness of the bone surrounding the maxillary teeth, as well as by individual variations in response to the drug administered. When only the anterior maxilla teeth are considered for the anesthetic, the local anesthetic volume ranges from 0.5 to 1.8 ml (2). Brunetto et al. reported that 1.2 ml of 2% lidocaine + 1: epinephrine induced faster onset of pulpal anesthesia, a higher success rate, and a longer duration of soft tissue/pulpal anesthesia of the maxilla (2). Cowan suggested that doses of less than 0.75 ml of 2% lidocaine + 1:80000 epinephrine were adequate for two adjacent teeth after maxillary infiltration. Noncontinuous anesthesia has been reported by other groups after inferior alveolar nerve block. This may be the result of the equilibrium between ionized and nonionized forms of the anesthetic, which results in periods of inadequate pulpal anesthesia (15). 5. Formulation Inferior alveolar nerve (IAN) block is the most frequently used method for achieving local anesthesia for mandibular procedures. However, IAN block does not always result in

13 A New and Enhanced Version of Local Anesthetics in Dentistry 5 successful pulpal anesthesia. Local anesthetics are chemical compounds that cause reversible blockade of nerve impulses. They are weak bases with pka values between 7.5 and 9.0, and their physicochemical properties largely determine their clinical anesthetic characteristics. Galindo et al. used ph-adjusted local anesthetic solutions (ph 7.4) in peripheral nerve block and regional anesthesia and reported better quality of anesthesia (16). Davies reviewed the relevant literature and concluded that buffering local anesthetics with sodium bicarbonate significantly reduced injection pain (17). Whitcomb et al. reported that buffering 2% lidocaine + 1: epinephrine with 0.17 meq/ml sodium bicarbonate did not significantly increase the success of anesthesia, provide faster onset, or result in less pain at injection compared with unbuffered 2% lidocaine + 1: epinephrine for inferior alveolar nerve block. They considered raising the ph of the anesthetic formulation to 7.9, which is the acid dissociation constant (pka) of lidocaine, thereby producing equal amounts of the cation and the base form. However, a pilot study of various formulations demonstrated irritating effects (cellulitis and tissue injury). They found that a concentration of 0.17 meq/ml of sodium bicarbonate raised the ph of the lidocaine formulation to 7.5 without causing an irritating effect. They used a total volume of 3.6 ml of the lidocaine/sodium bicarbonate formulation to allow more sodium bicarbonate to be used by volume than a volume of 1.8 ml would have allowed. Each subject received 72 mg of lidocaine by administration of unbuffered lidocaine, while use of buffered lidocaine resulted in administration of only 60 mg of lidocaine. Therefore, subjects in the buffered group received 17% less lidocaine. Although less lidocaine was administered to patients receiving the buffered formulation, the same success rate of anesthesia was achieved as with the unbuffered lidocaine formulation (18). Maxillary and mandibular infiltration anesthesia is a common method of anesthetizing maxillary and mandibular teeth. Katz et al. reported that success of anesthesia and onset of pulpal anesthesia were not significantly different among 2% lidocaine + 1: epinephrine, 4% prilocaine + 1: epinephrine, and 4% prilocaine for the maxillary lateral incisor and first molar. For both the lateral incisor and first molar, 4% prilocaine + 1: epinephrine and 2% lidocaine + 1: epinephrine showed equivalent pulpal anesthesia. However, neither agent provided 1 hour of pulpal anesthesia. For both the lateral incisor and first molar, 4% prilocaine provided a significantly shorter duration of pulpal anesthesia compared with 2% lidocaine + 1: epinephrine and 4% prilocaine + 1: epinephrine. Katz et al. suggested that the infiltration injection of 1.8 ml of 2% lidocaine + 1: epinephrine may not always be 100% successful because of individual variations in response to the drug administered, operator differences, and variations in anatomy and tooth position. The success rate of the infiltration of 4% prilocaine + 1: epinephrine was 90% in the lateral incisor and 93% in the first molar. The success of the infiltration of 4% prilocaine was 83% in the lateral incisor and 80% in the first molar and provided a shorter duration of pulpal anesthesia (19). The mandible is comprised of dense, thick cortical bone, and the efficacy of infiltration anesthesia for mandibular molars in dental procedures has therefore traditionally been considered inadequate. Abdulwahab et al. evaluated the efficacy of six local anesthetic formulations (2% lidocaine + 1: epinephrine (L100), 4% articaine + 1:200000

14 6 Clinical Use of Local Anesthetics epinephrine (A200), 4% articaine + 1: epinephrine (A100), 4% prilocaine + 1: epinephrine (P200), 3% mepivacaine without vasoconstrictor (Mw/o), and 0.5% bupivacaine + 1: epinephrine (B200) used for posterior mandibular buccal infiltration anesthesia. They showed that the maximum mean increases from baseline EPT measurements for the six formulations were 43.5% for L100, 44.8% for B200, 51.2% for P200, 66.9% for A200, 68.3% for Mw/o, and 77.3% for A100 (A100 vs. L100, P = 0.029). They reported that the mean VAS pain ratings for injection pain were 32.2 for B200, 27.6 for L100, 26.2 for A100, 24.1 for A200, 22.9 for Mw/o, and 21.0 for P200 (20). Inferior alveolar nerve block (IANB) is the most frequently used injection technique for achieving local anesthesia for mandibular restorative and surgical procedures. In asymptomatic patients, inferior alveolar nerve block fails 17 19% of the time in the first molar. Therefore, it would be advantageous to improve the success rate of the IANB technique. Additionally, slow onset of anesthesia occurs 12 19% of the time in the first molar with IANB and the use of articaine or lidocaine solutions. If supplemental buccal infiltration can reduce the failure rate and increase the speed of onset of pulpal anesthesia after IANB, the technique may be clinically useful. Haase et al. compared the anesthetic efficacy of articaine vs. lidocaine as supplemental buccal infiltration of the mandibular first molar after inferior alveolar nerve block. They found that with use of the 4% articaine + 1: epinephrine formulation, successful pulpal anesthesia was achieved for the first molar in 88% of cases. With the 2% lidocaine + 1: epinephrine formulation, successful pulpal anesthesia occurred in 71% of cases (21). Robertson and colleagues compared the degree of pulpal anesthesia achieved with mandibular first molar buccal infiltration of 4% articaine + 1: epinephrine and 2% lidocaine + 1: epinephrine. Using the lidocaine formulation, they achieved a success rate of 57% for the first molar. Using the articaine formulation, they achieved successful pulpal anesthesia in 87% of cases. The differences in rates achieved with 2% lidocaine and 4% articaine formulations were significant (P < 0.05). Therefore, 4% articaine + 1: epinephrine is superior to 2% lidocaine + 1: epinephrine in mandibular buccal infiltration of the first molar. However, Robertson and colleagues found that pulpal anesthesia with both the 4% articaine and 2% lidocaine formulations declined slowly over 60 minutes (22). Foster et al. investigated the anesthetic efficacy of buccal and lingual infiltrations of lidocaine following inferior alveolar nerve block in mandibular posterior teeth. They found that adding buccal or lingual infiltration of 1.8 ml of 2% lidocaine + 1: epinephrine to IANB did not significantly increase the success of anesthesia in mandibular posterior teeth (23). Pabst et al. investigated the efficacy of repeated buccal infiltration of articaine in prolonging the duration of pulpal anesthesia in the mandibular first molar. The degree of pulpal anesthesia obtained with two sets of mandibular first molar buccal infiltrations given in two separate doses was examined in 86 adult subjects: an initial infiltration of a cartridge of 4% articaine + 1: epinephrine plus a second infiltration of the same anesthetic and dose 25 minutes after the initial infiltration vs. an initial infiltration of a cartridge of 4% articaine + 1: epinephrine plus mock repeat infiltration given 25 minutes following the initial infiltration. The authors used an electric pulp tester to test the first molar for anesthesia in 3- minute cycles for 112 minutes after the injections. The repeated infiltration significantly

15 A New and Enhanced Version of Local Anesthetics in Dentistry 7 improved pulpal anesthesia from 28 minutes to 109 minutes in the mandibular first molar. Repeated infiltration of a cartridge of 4% articaine + 1: epinephrine given 25 minutes after the initial infiltration of the same type and dose of anesthetic significantly improved the duration of pulpal anesthesia in the mandibular first molar compared with initial buccal infiltration alone (24). Increasing attention has been focused on the clinical application of -2 adrenoceptor agonists for anesthetic management. Furthermore, various methods of administration, such as epidural, intrathecal, and peripheral injections, have been examined alone or in combination with another drug to prolong and intensify the anesthesia. The -2 adrenoceptor agonist, clonidine, combined with a local anesthetic, has been found to extend the duration of peripheral nerve block. The action of clonidine was suggested to be due to local vasoconstriction and/or direct inhibition of impulse conduction in peripheral nerves. However, the mechanism of action has not been fully elucidated. Clonidine is not particularly specific to -2 adrenoceptors and also acts via -1 adrenoceptors at comparatively high concentrations. Clonidine has the ability to induce vasoconstriction, and it is therefore unclear whether it acts via -2 adrenoceptors. On the other hand, another -2 adrenoceptor agonist, dexmedetomidine, acts more specifically against -2 adrenoceptors and has more than eight times greater affinity for -2 adrenoceptors of clonidine(25). It has sedative, analgesic, and sympatholytic effects that blunt many of the cardiovascular responses(hypertension, tachycardia) seen during the perioperative period (26). Dexmedetomidine has also been reported to enhance central and peripheral neural blockaded by local anesthetics; however, the peripheral effects have not been fully clarified. Yoshitomi et al. reported that dexmedetomidine and other -2 adrenoceptor agonists (oxymetazoline hydrochloride, yohimbine hydrochloride, prazosin hydrochloride) enhanced the local anesthetic action of lidocaine in the periphery (25). Ketamine is a well-known general anesthetic and short-acting intraoperative analgesic. Ketamine has multiple effects throughout the central nervous system, including blocking polysynaptic reflexes in the spinal cord and inhibiting excitatory neurotransmitter effects in selected areas of the brain. It dissociates the thalamus (which relays sensory impulses from the reticular activating system to the cerebral cortex) from the limbic cortex (which is involved with the awareness of sedation). While some brain neurons are inhibited, others are tonically excited. Clinically, this state of dissociative anesthesia causes the patient to appear conscious (eg, eye opening, swallowing, muscle contracture) but unable to process or respond to sensory input (26).This agent is a nonselective antagonist of supraspinal N- methyl-d-aspartate (NMDA) receptors, which are activated by the excitatory neurotransmitter glutamate. Inhibition of NMDA receptors decreases neuronal signaling and is likely responsible for some of the analgesic effects of ketamine. Satilmis et al. demonstrated that the combination of a local anesthetic and subanesthetic doses of ketamine during surgical extraction of third molars can produce good local anesthesia while affording a comfortable procedure for both surgeon and patient, providing good postoperative analgesia with reduced swelling and significantly less trismus than local anesthesia alone (27).

16 8 Clinical Use of Local Anesthetics Failure to achieve anesthesia can be a significant problem in dental practice. Studies have shown that more than 50% of adults in the USA miss dentistry services because of a fear of pain. Controlling patients anxiety and distress, good treatment of root canals, effective use of local anesthetics, and drug therapy cover the main factors in the management of dental pain. Amitriptyline is one of the most common tricyclic antidepressants (TCAs) and binds to pain sensory nerve fibers close to the sodium channels; hence, it may interact to some degree with receptors of local anesthetics. Although TCAs have been successfully used in the treatment of some types of neuropathic pain and they have been shown to have efficacy in blocking Na channels in the nervous system, they have not been used systemically for the completion of anesthesia in dental pain because of the potential risks of adverse drug reactions. However, topical use of a lipid-soluble TCA, e.g., amitriptyline, administered directly into the pulp cavity of a painful tooth in addition to routine local anesthetic injection may synergistically complete analgesia through coinhibition of Na channels on pain sensory fibers. Moghadamnia et al. reported that inter-pulp-space administration of 2% amitriptyline gel for completing analgesia in irreversible pulpitis pain was effective and useful as a conjunctive therapy to injection of local anesthetics (28). 6. References [1] Shahidi Bonjar AH. Syringe micro vibrator (SMV) a new device being introduced in dentistry to alleviate pain and anxiety of intraoral injections, and a comparative study with a similar device. Ann Surg Innov Res. 2011;5:1. [2] Brunetto PC, Ranali J, Ambrosano GM, et al. Anesthetic efficacy of 3 volumes of lidocaine with epinephrine in maxillary infiltration anesthesia. Anesth Prog. 2008; 55(2): [3] Milam SB, Giovannitti JA Jr. Local anesthetics in dental practice. Dent Clin North Am. 1984;28(3): [4] Sisk AL. Vasoconstrictors in local anesthesia for dentistry. Anesth Prog. 1992;39(6): [5] MacKenzie TA, Young ER. Local anesthetic update. Anesth Prog. 1993;40(2): [6] Yagiela JA. Recent developments in local anesthesia and oral sedation. Compend Contin Educ Dent. 2004;25(9): ; quiz 708. [7] Szabo G. In: Oral & Maxillofacial Surgery. Semmelweis Publishing House. Budapest p [8] Moore PA, Hersh EV. Local anesthetics: pharmacology and toxicity. Dent Clin North Am. 2010;54(4): [9] Berlin J, Nusstein J, Reader A, Beck M, Weaver J. Efficacy of articaine and lidocaine in a primary intraligamentary injection administered with a computer-controlled local anesthetic delivery system. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005;99(3): [10] Hawkins JM, Moore PA. Local anesthesia: advances in agents and techniques. Dent Clin North Am. 2002;46(4):719 32, ix.

17 A New and Enhanced Version of Local Anesthetics in Dentistry 9 [11] Kaufman E, Epstein JB, Naveh E, Gorsky M, Gross A, Cohen G. A survey of pain, pressure, and discomfort induced by commonly used oral local anesthesia injections. Anesth Prog. 2005;52(4): [12] Finder RL, Moore PA. Adverse drug reactions to local anesthesia. Dent Clin North Am. 2002;46(4):747 57, x. [13] Speca SJ, Boynes SG, Cuddy MA. Allergic reactions to local anesthetic formulations. Dent Clin North Am. 2010;54(4): [14] Malamed SF. Allergy and toxic reactions to local anesthetics. Dent Today. 2003;22(4):114 6, [15] Cowan A. Minimum dosage technique in the clinical comparison of representative modern local anesthetic agents. J Dent Res. 1964;43: [16] Galindo A. ph-adjusted local anesthetics: clinical experience. Reg Anesth. 1983;8:35 6. [17] Davies RJ. Buffering the pain of local anesthetics: a systematic review. Emerg Med (Fremantle) 2003;15:81 8. [18] Whitcomb M, Drum M, Nusstein J, Beck M. A prospective, randomized, double-blind study of the anesthetic efficacy of sodium bicarbonate buffered 2% lidocaine with 1:100,000 epinephrine in inferior alveolar nerve blocks. Anesth Prog 2010; 57(2): [19] Katz S, Drum M, Nusstein J, Beck M. A prospective, randomized, double-blind comparison of 2% lidocaine with 1:100,000 epinephrine, 4% prilocaine with 1:200,000 epinephrine, and 4% prilocaine for maxillary infiltrations. Anesth Prog 2010;57(2): [20] Abdulwahab M, Boynes S, Moore P, et al. The efficacy of six local anesthetic formulations used for posterior mandibular buccal infiltration anesthesia. J Am Dent Assoc. 2009;140(8): [21] Haase A, Nusstein J, Beck M, Drum M. Comparing anesthetic efficacy of articaine versus lidocaine as a supplemental buccal infiltration of the mandibular first molar after an inferior alveolar nerve block. J Am Dent Assoc. 2008;139(9): [22] Robertson D, Nusstein J, Reader A, Beck M, McCartney M. The anesthetic efficacy of articaine in buccal infiltration of mandibular posterior teeth. JADA 2007;138(8): Foster W, Drum M, Beck M. Anesthetic efficacy of buccal and lingual infiltrations of lidocaine following an inferior alveolar nerve block in mandibular posterior teeth. Anesth Prog. 2007;54(4): [23] Pabst L, Nusstein J, Drum M, Beck M. The efficacy of a repeated buccal infiltration of articaine in prolonging duration of pulpal anesthesia in the mandibular first molar. Anesth Prog. 2009;56(4): [24] Yoshitomi T, Kohjitani A, Maeda S. Dexmedetomidine enhances the local anesthetic action of lidocaine via an α-2a adrenoceptor. Anesth Analg 2008;107(1): [25] Morgan GE, Mikhail M, Murray M. In: Clinical Anesthesiology. Lange Medical Books/McGraw-Hill Medical Publishing Division. London p [26] Satilmis T, Garip H, Arpaci E, et al. Assessment of combined local anesthesia and ketamine for pain, swelling, and trismus after surgical extraction of third molars. J Oral Maxillofac Surg. 2009;67:

18 10 Clinical Use of Local Anesthetics [27] Moghadamnia AA, Partovi M, Mohammadianfar I et al. Evaluation of the effect of locally administered amitriptyline gel as adjunct to local anesthetics in irreversible pulpitis pain. Indian J Dent Res. 2009;20(1):3 6.

19 Local Anesthesia for Cosmetic Procedures 2 Dhepe V. Niteen Dermatosurgery Taskforce, IADVL, SkinCity, Post Graduate Institute of Dermatology and Lasers, Solapur, Maharashtra India 1. Introduction In recent years the number of cosmetic procedures is continuously increasing. Cosmetic procedure/surgery is an elective procedure. It is not an emergency. Hence not only final result but the overall comfort and satisfaction of the patient are equally important. Majority of the procedures are carried out under local anesthesia; so thorough knowledge of local anesthetic agents, types, techniques and their side effects becomes very much important for the aesthetic physicians. 1.1 Learning objectives At the end of reading of this chapter, reader should be able to understand the scope of various types of local anesthesia in his aesthetic practice, able to choose appropriate local anesthesia according to indication, able to do modification in various techniques according to the demand of situation to give pleasant and comfortable experience to patient during the aesthetic procedure while keeping in mind the possible adverse effects of the anesthesia. 1.2 Mechanism of local anesthetic activity Studies have shown that local anesthetics inhibit depolarization of the nerve by interfering with the influx of Na + ions. Although the exact mechanism of local anesthetic action is not known, several theories postulate that anesthetics diffuse across the neural membrane and somehow alter the activity of the Na + channel. Local anesthetics are thought to stabilize the membrane at resting potential, increase the threshold for electrical excitation, and reduce the propagation of an excitatory impulse, thereby blocking nerve conduction. 1 The sensation of pain is carried via small unmyelinated nerve fibers (C fibers). These fibers are more sensitive to the actions of local anesthetics as compared to larger nerve fibers that carry other sensations. Consequently patients may be able to feel sensations such as pressure and vibration, while being insensitive to pain Classification of local anesthetics Local anesthetics possess a basic chemical structure that gives it amphipathic characteristics. Its structure can be divided into three distinct parts: an aromatic portion (lipophilic),

20 12 Clinical Use of Local Anesthetics intermediate chain, and amine group (hydrophilic). The intermediate chain connects the aromatic group to the amine group. It is also the basis of local anesthetic classification as either esters or amides (Table 1). Ester anesthetics are metabolized via the plasma enzyme, pseudocholinesterase. Hydrolysis is rapid and the by-products are excreted in the urine. Amide anesthetics are metabolized primarily by the liver. They should be used with caution in patients with liver disease. 3 For detailed discussion on pharmacology of local anesthetic agents, kindly refer to the related chapter in this book. Group Generic name Trade name Onset of anesthesia Duration of anesthesia Available Concentration (%) Amides Lidocaine Xylocaine Rapid Moderate 0.5, 1.0, 2.0 Mepivicaine Carbocaine Rapid Moderate 1.0, 2.0 Bupivicaine Marcaine Slow Long 0.25, 0.5, 0.75 Etidocaine Duranest Rapid Long 0.5, 1.0 Esters Procaine Novacaine Rapid Short 0.5, 1.0, 2.0 Tetracaine Pontocaine Slow Long 0.1,0.25 Table 1. Common Local Anesthetics Used in Dermatology 2, Combination of Local anesthetics and adrenaline 5, 6 Many times local anesthetic is administered along with vasoconstrictor like adrenaline with beneficial results. This combination offers following advantages: 1. Decrease anesthetic absorption and systemic toxicity with improved efficacy and smaller amounts required. 2. Prolonged duration of action (almost doubled), especially with lignocaine and procaine 3. Less bleeding at operative site, especially useful on vascular areas with better visualization of operative field. Adrenaline may potentially induce adverse effects. Therefore its use must be carefully considered in patients with heart disease and those patients concomitantly taking ß- blockers. 7

21 Local Anesthesia for Cosmetic Procedures 13 Symptoms Treatment Central nervous system Lidocaine Drowsiness, circumoral Intravenous diazepam, oxygen numbness, tingling of tongue, metallic taste, diplopia, blurred vision, tinnitus, slurred speech, muscle twitching, shivering, seizure, respiratory arrest Epinephrine Nervousness, tremors, headaches Cardiovascular system Lidocaine Progressive myocardial Cardiopulmonary, depression, prolonged resuscitation, oxygen, conduction time, vasopressors, arteriovenous block, intravenous fluids bradycardia vasomotor depression, hypotension, hypoxia, acidosis Epinephrine Tachycardia, palpitations, Vasodilators (hydralazine, chest pain, hypertension clonidine, sublingual nifedipine) Allergic Lidocaine Urticaria, angioedema, Antihistamines, subcutaneous anaphylaxis epinephrine, oxygen, steroids Psychogenic Vasovagal response Table 2. Adverse Effects of Lidocaine with Epinephrine 8 2. Types of local anesthesia for cosmetic procedures 2.1 Topical anesthesia 9 Cold compresses on forehead and neck, Trendelenburg position, fan patient, ammonia ampule Topical anesthesia is the surface application of a LA to the skin or mucous membrane by means of a spray, spreading of an ointment,). Lidocaine 2% jelly, EMLA cream, or iontophoresis of lidocaine can allow one to perform simple procedures such as shave biopsies, electro-cauterization of epidermal growths or superficial laser surgery. Topical

22 14 Clinical Use of Local Anesthetics anesthetics can also provide surface anesthesia to permit painless insertion of a needle, especially in children, and on painful areas such as the nose, lips and genitalia Mucosal agents Topical anesthetics agents are useful on mucosal surfaces include cocaine 4%, benzocaine 5-20%,tetracaine 0.5% and lidocaine 2-5% (jelly, ointment), lidocaine 10% aerosol etc Cutaneous agents Creams: for producing an anesthesia on intact skin, creams of lidocaine (30%) or EMLA eutectic mixture of local anesthetics have to be applied for variable period of time (30min to 2 hours) according to the composition of the EMLA. This EMLA has to be applied under occlusion for its optimum effect. The list of commonly available topical anesthetic is given in Table 3. Special delivery techniques for topical anesthesia Iontophoresis 11 The introduction of various ions into the skin through the use of electricity has been increasingly used to provide pain relief in outpatient procedures. It uses an electric current to overcome some of the barriers of the skin and assist the penetration through the movement of ions into the skin via sweat glands, hair follicles and sebaceous glands. Iontophoresis can be used to deliver chemicals to both superficial and deeper layers of the skin. Advantages are 1. It avoids pain associated with injections. 2. It prevents the variation in absorption seen with oral medications 3. It bypasses first-pass elimination 4. Drugs with sorter half life can be delivered directly to the tissue Disadvantages are 1. Discomfort and erythema at the site of iontophoresis secondary to ph changes 2. There is also potential of skin irritation and burn Laser assisted delivery of Topical anesthetics: A research in 2003 indicates that a single pass of the Er:YAG laser (wave length 2940 nm) enhanced the absorption and penetration of lidocaine by disrupting the stratum corneum. 12 Although this technique may not be adequate for invasive procedures, it may minimize pain and discomfort for more superficial cutaneous procedure, such as hypodermic needle insertion. This is a well known fact that reapplication of topical anesthetic after first pass of ablative lasers produce quicker and deeper anesthesia. Interest in laser assisted drug delivery was reemerged after advent of fractional lasers. Narrow but deep vertical channels of ablation into skin created by fractional CO2 laser were used to successfully deliver a drug, methyl 5-aminolevulinate (MAL) to a uniform depth into skin. 13 The absoption was uniform and full thickness indicating drug delivery from lateral walls of the tunnel. Currently trials are under progress to use this method to deliver local anesthetic agent to skin.

23 Local Anesthesia for Cosmetic Procedures 15 Anesthetic Ingredients Vehicle Application Dose Occlusion required FDA approved Advantages Max Dose/ Disadvantages Area Betacain-LA Lidocaine Vaseline No No Anecdotal more clinical 300cm²- Prilocain ointment reports of and safty adults Dibucaine rapid onset trial needed LMX 4% Liposomal 60 No Yes Liposomal Post 100cm²- Lidocaine delivery application children long duration residue 600cm²of action 10kg-adult /children LMX 5 5% Liposomal 30 No Yes Rapid onset more clinical 100cm²- Lidocaine of action trails needed children 600cm²- 10kg-adult /children EMLA 2.5% Oil in water 60 Yes Yes Proven Long 20g/200cm² Lidocaine efficacy and application adult and 2.5% safety occlusion children older Prilocain profile required than 7 and >20 kg Tretracaine 4% Lecithin gel Yes No Anecdotal more clinical None gel Tretracaine reports of and safty reported Gel rapid onset trial needed Amethocaine 4% Yes No Rapid onset Ester 50mg-adult Tretracaine prolonged anesthetic, effect avoid mucosal surfaces Topicaine 4% Microemulsion Yes Yes Rapid onset more clinical 600cm²-adult Lidocaine Cost effective trial needed (children >10kg) S-Caine Lidocaine clinical delivery Ester determined 2.5% trails system anesthetic 2.5% Oil in water No Phase III Unique Contains as To be Tretracaine Table 3. Drugs used for topical anesthesia 14

24 16 Clinical Use of Local Anesthetics Needle-less Dermajet This is a needleless pressure injection syringe for the intradermal infiltration of drugs in a soluble state. This technique achieves almost painless tissue infiltration with a high velocity microspray in single or multiple doses of 0.1 cc. to a depth of 2 to 5 mm. without actual contact with the site of injection. A fine jet emitted under great pressure punctures the tissue without coring, with a minimum amount of trauma, raising instantaneously a well-defined pinpoint wheal. Besides giving local anesthesia this mode of drug delivery is useful in intralesional steroid injection in case of keloid and hypertrophic scar, in mass vaccinations 15 etc. Microporation Iontophoresis applies a small low voltage (typically 10 V or less) continuous constant current (typically 0.5 ma/cm 2 or less) to push a charged drug into skin or other tissue. In contrast, electroporation applies a high voltage (typically, >100 V) pulse for a very short (μs-ms) duration to permeabilize the skin. 16 Low frequency ultrasound is also used as sonoporation. 2.2 Infiltration anesthesia 9 This is the most commonly used method of anesthetizing the skin. It consists of injecting the anesthetic agent into the tissue to be cut. The injection may be intradermal, when the anesthesia is almost immediate, or into the subcutaneous tissue, when the anesthesia is usually delayed and has a shorter duration. However, an intradermal injection is more painful. The pain of a LA injection into the skin can be reduced by adding freshly prepared sodium bicarbonate (8.4%) solution to the LA solution in a 1:10 dilution. Local pain can also be reduced by injecting the drug slowly, while pinching the neighboring skin to distract the patient. The infiltration may distort the operative site; this can be minimized by gentle massage after the injection. 2.3 Field blocks 9 A field or ring block is a variation of infiltration anesthesia. The LA agent is placed around the operative site, anesthetizing the nerve fibers leaving from the area. A ring block is useful when direct needle entry into a lesion such as a cyst is not desirable. The LA has to be placed in both superficial and deep planes. Start injecting from proximal to distal end. This also limits the amount of LA needed to anesthetize the operative site. This is a particular advantage when a large area has to be anesthetized. 2.4 Peripheral nerve blocks A nerve block involves placing the local anesthetic solution in a specific location at or around the main nerve trunk that will effectively depolarize that nerve and obtund sensation in the area of sensory distribution of that particular nerve. In dermatological surgery, the commonly employed nerve blocks are for the digits and for the central face, because both areas are painful to anesthetize using local infiltration. Peripheral nerve blocks are difficult to perform and complications include laceration of the nerve, intravascular injection of LA and hematoma formation may occur.

25 Local Anesthesia for Cosmetic Procedures 17 Advantages of nerve blocks include the fact that a single accurately placed injection can obtund large areas of sensation without tissue distortion at operative site. Disadvantages of peripheral nerve blocks include the sensation of numbness in areas other than the operative site and the lack of hemostasis at the operative site from the vasoconstrictor component of the local anesthetic injection. Since many nerves are accompanied by corresponding veins and arteries, pre-injection aspiration should always be performed to prevent intra vascular injection. Use of local anesthetics with vasoconstrictors will prolong anesthesia. 3. Sensory nerves and respective dermatomes of face and their block 3.1 Fig 1a and 1b Sensory innervations of face and neck area Trigeminal nerve Often referred to as the great sensory nerve of the head and neck, the trigeminal nerve is named for its three major sensory branches. The ophthalmic nerve (VI), maxillary nerve (V2), and mandibular nerve (V3) are literally three twins (trigeminal) carrying sensory information of light touch, temperature, pain, and proprioception from the face and scalp to brainstem. The main branches of the trigeminal nerve supply sensation to the well defined and consistent facial areas. Fig. 1a.

26 18 Clinical Use of Local Anesthetics Fig. 1b. 3.2 Anatomic arrangement of facial foramina Successful nerve block anesthesia is largely dependent upon knowing the position of the nerve foramina. The surgeon can take advantage of the alignment of the major facial foramina as they relate to a vertical line through the mid pupillary line with the eye in the primary position of natural forward gaze. 3.3 Common nerve blocks Supraorbital nerve The supraorbital nerve exits through a notch (in some case a foramen) on the superior orbital rim approximately 27 mm lateral to the glabellar midline. This supraorbital notch is readily palpable in most patients. After existing the notch or foramen, the nerve traverses the corrugator supercilii muscles and branches into a medical and lateral portion. The lateral branches supply the lateral forehead and the medial branches supply the scalp. 2. Supratrochlear nerve and Supraorbital The supratrochlear nerve exits a foramen approximately 17 mm from the glabellar midline and supplies sensation to the middle portion of the forehead. The infratrochlear nerve exits a foramen below the trochlea and provided sensation to the medial upper eyelid, canthus, medial nasal skin, conjunctiva, and lateral lacrimal apparatus. When injecting this area it is prudent to always use the nondominant hand to palpate the orbital rim to ensure that the needle tip is exterior to the bony orbital margin. To anesthetize this area, the supratrochlear nerve is measured 17 mm from the glabellar midline and 1-2 ml of local anesthetic is injected. The supraorbital nerve is blocked by palpating the notch (and/or measuring 27 mm from the glabellar midline) and injecting 1-2 ml of local

27 Local Anesthesia for Cosmetic Procedures 19 anesthetic solution. The infratrochlear nerve is blocked by injecting 1-2 ml of local anesthetic solution at the junction of the orbit and the nasal bones. Fig. 2. Supra orbital nerve block 3.4 Infraorbital nerve block This block is one of the most commonly utilized facial blocks in order to anesthetize the upper lip and upper nasolabial fold for injection of fillers. Obviously, a bilateral block must be performed to achieve anesthesia on both sides of the lip. The Infraorbital nerve exits the Infraorbital foramen 4-7 mm below the orbital rim in an imaginary line dropped from the midpupillary midline. The anterior superior alveolar nerve branches from the Infraorbital nerve before it exits the foramen, and thus some patients will manifest anesthesia of the anterior teeth and gingival if the branching is closed to the foramen. Areas anesthetized include the lateral nose, anterior cheek, lower eyelid, and upper lip on the injected side. This nerve can be blocked by intraoral or extraoral routes. To perform an Infraorbital nerve block from an intraoral approach, (fig 3) topical anesthesia is placed on the oral mucosa at the vestibular sulcus just under the canine fossa (between the canine and first premolar tooth) and left for several minutes. The lip is then elevated and a ½ inch 30 gauge needle is inserted in the sulcus and directed superiorly towards the Infraorbital foramen. Bending the needle at 45 degree angle upward can facilitate the needle insertion. The needle needs only to approach the vast branching around the foramen to be effective. It is important to use the other hand to palpate the inferior orbital rim to avoid injecting superiorly the orbit. 2-4 ml of 2% lidocaine is injected in this area for the Infraorbital block and the palpating finger can feel the local anesthetic bolus below the Infraorbital rim, confirming the correct are of placement. The Infraorbital nerve can also be very easily blocked by the transcutaneous facial approach and may be the preferred rout in dental phobic patients. (fig 4). A 32 gauge ½ inch needle is used and is placed through the skin and aimed at the foramen in a perpendicular direction. Between 2 and 4 ml of local anesthetic solution is injected at or close to the foramen. Again,